Transplanters are well known in the art. U.S. Pat. No. 6,327,986 discloses an apparatus for transplanting seedlings from nursery trays. This approach utilizes a specially designed tray with grooves evenly spaced across the tray top for a sprocket-type element to engage and incrementally advance the tray one row at a time into the extraction area. At the extraction area, a row of plunger devices engage the tray and push one row of plants at a time from the tray into an endless belt equipped with a series of chambers that are matched to the same pitch center of the tray. After extraction, the loaded root ball chambers and belt assembly are rotated 90° from the face of the tray. The plants are then discharged, one at a time, into a series of interlocks that convey the plants to the ground engaging row unit. Along the way, three separate sets of sensors look for plant skips and advance the root ball chamber belt assembly one cell to make up for skips and eject the deficient root ball at the same time.
U.S. Pat. No. 6,080,951 discloses another approach to overcome the seedling tray skip problem. This concept utilizes a system, whereby two sets of plungers and extractors remove plants simultaneously from a plant tray. On a 10 cell tray, the first extractor would be positioned at the No. 1 cell and the second at the No. 6 cell. After extraction, the plants are dropped into two separate gated chambers and sensors confirm that plants are present. In normal operation, the plants would discharge sequentially from each chamber. If a skip is detected, the deficient root ball would be discarded and the other root ball would be planted in its place.
These approaches rely heavily on the accuracy of detectors to sense the presence of plant foliage. Considering the chaotic nature of the foliage and the necessary speed to be efficient, there is substantial room for error in these systems. Our system, by nature of its design, has no sensors, no extra extraction points or extra mechanics. All the tray skips are overcome by the belts pushing together the root balls of the rows of plants extracted from a plant tray.
Other transplanters which transplant from a plant tray are shown in U.S. Pat. Nos. 4,644,880; 5,431,116; 5,573,558; 5,676,072; 6,073,564; and 6,634,306.